Surgical adhesions are abnormal fibrous bands of scar tissue that can form inside the body as a result of the healing process that often follows open or minimally invasive surgical procedures including abdominal, gynecologic, cardiothoracic, spinal, plastic, vascular, ENT, ophthalmologic, urologic, neuro, or orthopedic surgery.
Surgical adhesions are typically connective tissue structures that form between adjacent injured areas within the body. Briefly, localized areas of injury trigger an inflammatory and healing response (clotting) that culminates in healing and scar tissue formation. If scarring results in the formation of fibrous tissue bands or adherence of adjacent anatomical structures (that should normally be separate), adhesion formation is said to have occurred.
Adhesions can range from flimsy, easily separable structures to dense, tenacious fibrous structures that can only be separated by surgical dissection. While many adhesions are benign, many adhesions can cause major pain. For example, adhesions to nerve structures (i.e. nerve root, spinal cord) and other vital structures after spinal surgery result in post-operative pain and make revision surgery difficult and potentially dangerous if necessary. More specifically, after spinal surgery if adhesions form they may cause tethering of spinal nerve roots and dorsal root ganglia, which often causes recurrent radicular pain that can be very debilitating to the patient and often leads to repeated surgical intervention.
Since most surgery involves a certain degree of trauma to the operative tissues, virtually any procedure (no matter how well executed) has the potential to result in the formation of clinically significant adhesion formation. Adhesions can be triggered by surgical trauma such as cutting, manipulation, retraction or suturing, as well as from inflammation, infection (e.g., fungal or mycobacterium), bleeding or the presence of a foreign body. Surgical trauma may also result from tissue drying, ischemia, or thermal injury. Due to the diverse etiology of surgical adhesions, the potential for formation exists regardless of whether the surgery is done in a so-called minimally invasive fashion (e.g., catheter-based therapies, laparoscopy) or in a standard open technique involving one or more relatively large incisions. Although a potential complication of any surgical intervention, surgical adhesions are particularly problematic in GI surgery (causing bowel obstruction), gynecological surgery (causing pain and/or infertility), tendon repairs (causing shortening and flexion deformities), joint capsule procedures (causing capsular contractures), and nerve and muscle repair procedures (causing diminished or lost function).
Surgical adhesions may cause various, often serious and unpredictable clinical complications; some of which manifest themselves only years after the original procedure was completed. Complications from surgical adhesions are a major cause of failed surgical therapy and are the leading cause of bowel obstruction and infertility. Other adhesion-related complications include chronic back or pelvic pain, intestinal obstruction, urethral obstruction and voiding dysfunction.
Relieving the post-surgical complications caused by adhesions generally requires another surgery. However, the subsequent surgery is further complicated by adhesions formed as a result of the previous surgery. In addition, the second surgery is likely to result in further adhesions and a continuing cycle of additional surgical complications.
Other surgical complications can occur when there is a need to enhance bone formation or bone growth. These surgical complications may occur in conditions, such as for example, bone segmental defects, periodontal disease, metastatic bone disease, osteolytic bone disease and conditions where connective tissue repair would be beneficial, such as healing or regeneration of cartilage defects or injury.
One particular condition characterized by a need to enhance bone growth is spinal disc injury. Various bone inductive factors have been employed to stimulate bone growth. For example, bone morphogenic proteins (BMPs) are novel factors in the extended transforming growth factor beta superfamily. Bone inductive factors are useful in that they can facilitate bone growth to treat various conditions requiring bone growth. However, ungoverned bone growth triggered by such bone inductive factors can also be problematic. For example, an effective method of treating spinal disc injury is a discectomy, or surgical removal of a portion or all of an intervertebral disc followed by fusion of the adjacent vertebrae. The fusion is often accomplished by locking the adjacent vertebrae together with a spinal cage, and administering a bone inductive factor (e.g., BMP) in between the vertebrae to facilitate bone growth and fusion of the adjacent vertebrae. However, the administered bone inductive factor may cause bone growth in the spinal canal, which in turn may cause additional problems including increased intraspinal pressure and pinched nerves.
Such problems may be attenuated or eliminated with a method for governing bone growth, and directing the growth away from unwanted areas, such as areas within the spinal canal. Thus, there is a need for improved methods and compositions for reducing or inhibiting bone growth in undesired parts of the body.